Steam Controller announced

Today, Valve revealed the final piece of their plans to take over the living room. It's a controller.

Today, Valve revealed the final piece of their plans to take over the living room. The SteamOS-powered Steam Machine will be compatible with a new Valve-developed controller.
"We also think that a controller that has higher precision and lower latency is another interesting thing to have," Valve head Gabe Newell said earlier this year. According to Valve, their controller offers a "vastly superior control scheme" due to their focus on low-latency performance. The controller will be designed to work every game on Steam.
Unlike most standard controllers, dual analog sticks have been replaced with dual trackpads that are also clickable. "Steam gamers, who are used to the input associated with PCs, will appreciate that the Steam Controller's resolution approaches that of a desktop mouse," Valve notes in their announcement. Of course, trackpads aren't traditionally the most comfortable tech to use, and Valve addresses those problems by adding haptic feedback to the device. "They are capable of delivering a wide range of force and vibration, allowing precise control over frequency, amplitude, and direction of movement," Valve says. The haptic feedback is also capable of playing audio waveforms.

An example of how the controller can be mapped

The center of the controller also features a touch screen. However, unlike the DualShock 4 from PlayStation, it is actually a high-resolution screen, not just a trackpad. Like the DS4, the screen is also clickable. Additionally, because Valve doesn't want to distract players with the screen, a display will be overlayed on the TV whenever the player touches the screen.
Obviously, the controller will work on any PC, not just "Steam Machines." However, prototype controllers will ship with the 300 beta units Valve plans on shipping later this year. Early versions of the controller won't be wireless and they won't include the touch screen.
Surprisingly, the controller does not feature support for biometric data, in spite of Valve's keen interest in it. "Biometrics on the other hand is essentially adding more communication bandwidth between the game and the person playing it, especially in ways the player isn't necessarily conscious of. Biometrics gives us more visibility," Newell said earlier this year.
The Steam Controller has not been priced.